Accommodative intraocular lens

ABSTRACT

The invention concerns an accommodative intraocular lens for capsular bag comprising a central optical part and a peripheral haptic part, the optic part having an forward position for accommodation and a rest position for far vision. The invention is characterized in that the haptic part ( 20 ) comprises a radially extending zone for displacing the optic part ( 10 ) towards the forward position. The radially extending zone ( 21 ) may include a gusset ( 22 ) with at least one crimp and/or made of a more flexible material than the remainder of the haptic part.

The present invention relates to intraocular lenses, also known asintraocular implants, designed to replace crystalline lenses affected bycataracts, after ablation thereof, and more particularly toaccommodative intraocular lenses.

The intact crystalline lens enables a person to see close up or far awaythanks to the mechanism known as accommodation. Accommodation is linkedto the variation in the shape of the crystalline lens by contraction ofthe ciliary muscle. This mechanism is still not fully understood.

According to the most widely accepted theory, put forward by Helmholtz,during accommodation, the contraction of the ciliary muscle leads torelaxation of the zonular fibers attached to the equator of the capsularsac of the crystalline lens. This relaxation allows the crystalline lensto “bulge”, the radii of curvature of the anterior and posterior facesdecreasing, thereby increasing the power or vergence of the crystallinelens. Similarly, during accommodation, the anterior face of thecrystalline lens moves forward, towards the cornea, because of vitreousthrust induced by an increase in pressure.

There are other theories of the accommodation mechanism. According tothat of Schachar, which contradicts that of Helmholtz, the contractionof the ciliary muscle tensions the zonule, which is said to applytraction at the equator and to be responsible for the deformation of thecentral part of the crystalline lens.

Similarly, the role of the vitreous in accommodation is controversial.According to some, the vitreous opposes modification of the shape of theposterior face of the crystalline lens during accommodation butcontributes to forward movement of the crystalline lens in the directionof the cornea.

Moreover, presbyopia reduces the accommodation capacity of the naturalcrystalline lens, and mutually consistent studies have shown that thecontraction of the ciliary muscle is at least partially preserved when aperson suffers from presbyopia.

The ablation of the crystalline lens is usually effected by capsulotomyof the anterior capsule or leaf of the capsular sac, followed byphacoemulsification of the crystalline lens and cleaning of the site.Thereafter, the implant is introduced into the interior of what remainsof the capsular sac, namely the posterior capsule and the remainingannular peripheral portion of the anterior capsule. The natural kineticsof accommodation are affected by the capsulotomy, the extraction of thecrystalline lens and, to a lesser degree, the implanting of anintraocular lens.

However, accommodative intraocular lenses have been designed to exploitremaining forces in a pseudophakic eye, i.e. after extraction of thecrystalline lens and implantation of an intraocular lens. Theseaccommodative intraocular lenses have not given full satisfaction, inparticular because there is insufficient displacement in theposterior-anterior direction with the new kinetics of the capsular sacof a pseudophakic eye.

The document WO 97/43984 describes an intraocular lens having anelastically deformable intermediate region for modifying the angle ofinclination of this zone relative to a plane normal to the optical axisof the lens and therefore having insufficient accommodation. The sameapplies to the document WO 01/60286 in which an intraocular lens ishinged to a shoe.

The present invention aims to overcome the drawbacks referred to above.It consists in a novel accommodative intraocular lens better able toexploit the new kinetics of the capsular sac of a pseudophakic eye andin particular the vitreous hyperpressure. The contraction of the ciliarymuscle that is at the root of the accommodation mechanism induces anincrease in the vitreous pressure. The vitreous is surrounded by thesclerotic, which is substantially undeformable, and by the posteriorcapsule, which is deformed as a result of the increase in the vitreouspressure. According to Dr Coleman (“On the hydraulic suspension theoryof accommodation” Tr. Am. Opht. Soc. Vol. 84, 1986), the variation ofvitreous pressure in primates during accommodation is from 2 to 10 cm ofwater, i.e. from approximately 200 Pa to approximately 1000 Pa. Pressurevariations of this magnitude would cause a displacement in theposterior-anterior direction from approximately 0.5 mm to approximately2 mm, i.e. sufficient movement for good accommodation by an intraocularlens.

The new kinetics also involve displacement of the apex of the ciliarymuscle and of the equator of the crystalline sac, both radially towardsthe optical axis of the eye and in the anterior direction. One object ofthe present invention is to exploit this conjoint and lineardisplacement of the apex of the ciliary muscle and the equator of thecrystalline sac to induce accommodation of an intraocular lens.

The present invention provides an accommodative intraocular lens forimplantation in the capsular sac comprising a central optical part and aperipheral haptic part, the optical part having a forward position foraccommodation and a rest position for far vision, characterized in thatthe haptic part comprises a radial expansion zone for displacing theoptical part towards the forward position.

In practice this zone is situated between the peripheral edge portion ofthe optical part and that of the haptic part. It may extend over thewhole or a portion of the radial distance between the peripheral edgeportion of the optical part and the peripheral edge portion of thehaptic part. Its circumference is preferably the same as thecircumference of the haptic part inside which it is situated.

The expansion potential of the radial expansion area as determinedbetween a point on the periphery of the optical part and a point on thesame radius on the periphery of the haptic part is from 0.2 mm to 1.6mm. This expansion potential of the radial expansion area allows axialdisplacement of the optical part of from 0.8 mm to 2.0 mm to providegood accommodation of near vision. The elasticity of the radialexpansion zone in the forward accommodation position returns the opticalpart to the rest position for far vision. In a preferred embodiment ofthe invention, the radial expansion zone comprises a bellows. In otherwords, this radial expansion zone comprises at least one undulation andis substantially annular or circumferential, possibly being interruptedby a plurality of radial notches opening onto the periphery of thehaptic part, to encourage posterior-anterior displacement, orinterrupted by gaps between radial arms constituting haptic membersextending between the peripheral edge portion of the optical part andthat of the haptic part.

In one preferred embodiment, the bellows comprises at least twoundulations, one opening in the anterior direction and the other in theposterior direction, the one opening in the anterior directionpreferably being disposed at the periphery of the optical part.

In one embodiment of the invention, the peripheral edge portion of thehaptic part has posterior and anterior right angles.

In a different embodiment, the haptic part comprises a peripheral gutterto provide separation parallel to the optical axis between the remainderof the anterior capsule and the posterior capsule of a pseudophakic eye.

In another embodiment, the radial expansion zone is made from a lessrigid material, and thereby constitutes a more flexible zone, with theresult that expansion results from stretching of this more elasticmaterial. Moreover, the bellows may be made at least in part from amaterial of higher elasticity, so that expansion results both fromflattening of the undulations or bellows and stretching of the part madefrom a material having a higher elasticity.

In one preferred embodiment, the haptic part comprises at least twohaptic members, each with a radial expansion zone comprising a bellowsor one or more undulations and/or made from a material having a higherelasticity. These haptic members preferably have a circumference attheir periphery that is greater than their circumference at the junctionwith the optical part.

Features and advantages of the invention will emerge from the followingdescription, which is given by way of example and with reference to theappended drawings:

FIG. 1 is a view of a first embodiment of an accommodative intraocularlens of the present invention in section taken along the line I-I inFIG. 2;

FIG. 2 is a front view of the FIG. 1 intraocular lens;

FIG. 3 is a view of a second embodiment in section taken along the lineIII-III in FIG. 4;

FIG. 4 is a front view of the FIG. 3 intraocular lens;

FIG. 5 is a view of a third embodiment in section taken along the lineV-V in FIG. 6;

FIG. 6 is a front view of the FIG. 5 intraocular lens;

FIG. 7 is a view in section of the accommodative intraocular lens fromFIGS. 1 and 2 showing the expansion of the radial expansion zone of thehaptic part (shown in continuous line) relative to the restconfiguration (shown in chain-dotted line);

FIG. 8 is a view in section of the accommodative intraocular lens fromFIGS. 3 and 4 showing the expansion of the radial expansion zone of thehaptic part (shown in continuous line) relative to the restconfiguration (shown in chain-dotted line);

FIG. 9 is a view in section of the accommodative intraocular lens fromFIGS. 5 and 6 showing the expansion of the radial expansion zone of thehaptic part (shown in continuous line) relative to the restconfiguration (shown in chain-dotted line);

FIGS. 10 and 11 show the FIG. 1 intraocular lens implanted in the eyeand respectively in the rest position and the accommodation position;

FIGS. 12 and 13 show the FIG. 3 intraocular lens implanted in the eyeand respectively in the rest position and the accommodation position;

FIGS. 14 and 15 show the FIG. 5 intraocular lens implanted in the eyeand respectively in the rest position and the accommodation position;

FIG. 16 is a front view analogous to FIG. 2 of a variant of the firstembodiment in which the haptic part comprises a plurality of radialnotches;

FIG. 17 is a view analogous to FIG. 2 of a second variant of the firstembodiment in which the haptic part comprises a plurality of bossesalong the circumference adapted to face the equator of the capsular sac;

FIG. 18 is a front view analogous to FIG. 6 of a variant of the thirdembodiment in which the haptic part comprises two haptic bellowsmembers;

FIG. 19 is a view analogous to that of FIG. 1 of another variant of theaccommodative intraocular lens;

FIG. 20 is a front view of the FIG. 19 intraocular lens;

FIG. 21 is a view of a preferred embodiment of an accommodativeintraocular lens in section taken along the line XXI-XXI in FIG. 22; and

FIG. 22 is a front view of the FIG. 21 intraocular lens.

In the embodiment shown in FIGS. 1 and 2, the accommodative intraocularlens 1 comprises a central optical part 10 having an optical axis A-Aand a peripheral haptic part 20 extending circumferentially around theoptical part. The intraocular lens is preferably made entirely or partlyfrom flexible material, such as a hydrophilic acrylic or polyHEMA.However, any other flexible material used for the production ofintraocular lenses may be used. As shown here, the optical part 10 isbiconvex. It may have other shapes, in particular plano-convex, or evenconcave-convex. The posterior face of the optical part is preferablyconvex and conformed to espouse the central region of the posteriorcapsule and thereby assure good transmission of vitreous hyperpressure.

The peripheral edge portion of the optical part may be provided with asharp annular edge projecting to the rear to reduce migration ofepithelial cells between the optical part and the posterior capsule.

According to the invention, the haptic part 20 comprises a radialexpansion zone 21. In this first embodiment, the radial expansion zone21 comprises a bellows 22 or one or more undulations, of which the firstundulation 23 is open on the anterior side and is situated in theimmediate vicinity of the periphery 11 of the optical part 10. Thisfirst annular undulation 23 is surrounded by a second annular undulation24 that is open on the posterior side and surrounded by a third annularundulation 25 that is open on the anterior side. In this embodiment, thefirst two undulations have substantially the same configuration,although extending in opposite directions, while the third undulation 25is narrower in the radial direction than the other two undulations. Inthis embodiment, the bellows 22 has a substantially sinusoidal shapeextending from the periphery 11 of the optical part to the peripheraledge portion 26. In a variant that is not shown, the bellows may have asomewhat more sawtooth shape.

In another variant that is not shown, the third undulation is replacedat least in part by a substantially plane annular zone continuous withthe peripheral edge portion 26, which is preferably annular andcontinuous, and has a substantially rectangular section, with a radialdimension, for example 0.6 mm, greater than its axial dimension, forexample 0.3 mm. The external edge of the peripheral edge portion 26 hasan anterior sharp or square corner edge 27 and a posterior sharp orsquare corner edge 28. The radial expansion zone 21 forming the bellows22 or comprising one or more undulations preferably has a substantiallyconstant thickness from the periphery of the optical part 11 to theperipheral edge portion 26. The depth of the first two undulations isthe same and from approximately 0.40 mm to approximately 0.70 mm and thesubtended angle is from approximately 50′ to approximately 70°.

In a second preferred embodiment, shown in FIGS. 21 and 22, the hapticpart 20 comprises two haptic members 20F extending in oppositedirections from the peripheral edge portion 11F of the optical part 10F.Each of these haptic members 20F has substantially the same radialsection as the haptic part 20 of the embodiment shown in FIGS. 1 and 2.The corresponding parts are designated by the same reference numberswith the suffix F. The circumference of each haptic member 20F isgreater at the peripheral edge portion 26F of the haptic part 20 thanthe circumference of the haptic member 20F at the junction with theoptical part 10F, so as to facilitate forward deformation. Each of thesehaptic members preferably subtends an angle of 90°, so that the gapsdefined by the opposite lateral edges of the two haptic members alsosubtend an angle of 90°. With an embodiment of this kind, the surgeon isable, after implantation, to access the site via gaps 29F formed betweenthe haptic members 20F to clean the posterior chamber beyond theimplant.

The haptic part 20F of an embodiment of this kind is more flexible thanthe haptic part 20A of the first embodiment because it is divided intotwo haptic members 20F of reduced circumference. This increasedflexibility, in the radial expansion zone 21F in particular, increasesfrom the periphery of the haptic part towards the periphery of theoptical part, thanks to the orientation of the lateral edges of thehaptic members, whilst allowing good retention of the haptic part in thecapsular sac thanks to the circumference of these haptic members at thelevel of the peripheral edge portion.

At least the major part of the lateral edges 29F of the haptic members20F is substantially radial because, as shown here, the portion of thelateral edges corresponding to the junction zone of each haptic member20F is slightly flared where it approaches the optical part 10F.Likewise, one or more of these lateral edges may be provided with anotch as a marker for checking that the implant is correctly oriented.

The overall diameter of an intraocular lens of the above kind ispreferably slightly greater than the diameter of the capsular sac at thelevel of the equator.

In a variant of this embodiment that is not shown, the haptic partcomprises three or even four haptic members of the same general shape asthe haptic members of the embodiment shown in FIGS. 21 and 22, with thecircumference of, and the gaps between, the haptic members reducedproportionately.

In a variant shown in FIG. 18 of the second embodiment shown in FIGS. 21and 22, the haptic part 20 comprises two haptic members 20C extending inopposite directions from the peripheral edge portion 11C of the opticalpart 10C. Each haptic member 20C has the same radial section as thehaptic part 20 of the embodiment shown in FIGS. 1 and 2. Thecorresponding parts are designated by the same reference numbers withthe suffix C.

In a variant shown in FIG. 16 of the first embodiment shown in FIGS. 1and 2, the haptic part 20 has a plurality of notches 27A disposedsymmetrically about the optical axis A-A of the implant. Thecorresponding parts of the embodiment shown in FIGS. 1 and 2 aredesignated by the same reference numbers with the suffix A. The notchespass partly or completely through the annular undulations. The hapticpart 20 is preferably provided with four notches 27A disposed at 90° toeach other about the optical axis. Each of the notches 27A has a closed,rounded and preferably semicircular interior end 28A approximately 1 mmfrom the edge of the periphery 11A of the optical part 10 and oppositeand parallel rectilinear edges 29A extending from the rounded end in amore or less radial direction and as far as the peripheral edge portion26A of the haptic part 20.

In another variant shown in FIGS. 19 and 20 of the first embodimentshown in FIGS. 1 and 2, the haptic part 20 comprises a plurality ofradial arms and three arms 20D each arm extending in the radialdirection between the peripheral edge portion 11D of the optical part 10and the peripheral edge portion 26D of the haptic part 20. Each of theradial arms 20D has the same radial section as the haptic part 20, thecorresponding parts of the embodiment shown in FIGS. 1 and 2 having thesame reference numbers with the suffix D. In this variant, the hapticarms 20D have a greater circumferential width at the junction with theperipheral edge portion 26D than at the junction with the peripheraledge portion of the optical part 11D. As shown here, these radial armssubtend an angle at the center of 60°. The gaps between the radial armssubtend the same angle at the center. The angle that the radial armssubtend at the center is preferably from 40° to 80°. Moreover, thelateral edges of the radial arms may be parallel to each other. In allcases, the width of each of the arms should be greater than or equal to1 mm. In the embodiment shown in FIGS. 19 and 20 the surgeon is able,after implantation, to access the site through the closed contour gaps29 formed between the radial arms 20D.

As shown diagrammatically in FIG. 7, in the first and second embodimentsthe length L1 of the haptic part 20 between the periphery 11 of theoptical part and the peripheral edge portion 26 of the radial expansionzone 21 at rest is of the order of 2.5 mm to 3.0 mm and alwayssignificantly less than the length L2 of the haptic part 20 between theperiphery 11 of the optical part and the peripheral edge portion 26 ofthe radial expansion zone 21 in the expanded state, which is of theorder of 3 mm to 4 mm after reduction or elimination of the undulations.The same applies to the variants of these embodiments.

FIGS. 10 and 11 show an accommodative intraocular lens 1 conforming tothe first embodiment shown in FIGS. 1 and 2 and to the second embodimentshown in FIGS. 21 and 22 and to variants thereof implanted in a capsularsac SC following ablation and phacoemulsification of the crystallinelens and cleaning of the site. It may be inserted through a smallincision in the sclerotic/cornea if the optical part and the haptic partare made at least in part from flexible material, such as an acrylic orhydrophilic polyHEMA silicone. This kind of implant may be folded orrolled in order to pass it through a small incision before it isdeployed in the posterior chamber of the aphakic eye. Any folding orinjection device may be used, and in particular an injector. In the restposition for far vision, shown in FIG. 11, anterior and posterior sharpedges or square corners 27, 28 at the outside edge 20 of the peripheraledge portion 26 are in contact with the capsular sac. The square cornersare intended to limit or inhibit proliferation of epithelial cells, inparticular on the posterior capsule, responsible for opacification ofthe latter, known as a secondary cataract, and necessitating YAG lasersurgery. In this position, the radial expansion zone 21 is normallyprestressed, because the overall diameter of the implant is slightlygreater than the diameter of the capsular sac SC at the level of theequator. As shown here, the center of the convex posterior face of theoptical part 10 is in contact with and espouses the posterior capsuleCP, which maximizes the transmission of vitreous pressure, which isapplied immediately to the optical part during pseudoaccommodation ofthe eye.

For near vision, the combination of the vitreous pressure in thecorresponding central region of the optical part concomitant withdisplacement of the apex of the ciliary muscle and the equator of thecapsular sac, both radially towards the center and axially forwards,encourages the displacement of the optical part 10 towards the forwardaccommodation position, as shown in FIG. 11. Application of vitreoushyperpressure and displacement of the apex of the ciliary muscle stretchthe radial expansion zone 21, and the undulations 23, 24 and 25 of thebellows 22 are therefore flattened or even eliminated when the opticalpart is in the maximum accommodation position. The radial expansion zone21 therefore adopts a globally frustoconical shape. It goes withoutsaying that if the vitreous hyperpressure were less than approximately200 Pa, one or more partially flattened undulations would remain.

For far vision, the apex of the ciliary muscle and the equator have thereverse kinetics, and the vitreous hyperpressure falls to the restvitreous pressure, thereby reducing the forces acting both on theperipheral edge portion 29 and on the optical part 10. The haptic part20 therefore resumes its rest configuration, by virtue of the radialexpansion zone returning to its initial position, as shown in FIG. 10.In the rest position the optical part is preferably slightly forward of,or where applicable in, a plane perpendicular to the optical axispassing through the middle of the area of contact of the peripheral edgeportion of the haptic part with the capsular sac. The variants of thisembodiment function in the same way as has just been described.

FIGS. 3 and 4 show a third embodiment of an accommodative intraocularlens. It comprises an optical part 30 and a haptic part 40. The opticalpart 30 shown has a biconvex shape but may have other shapes, as alreadyindicated.

In the embodiment shown in FIGS. 3 and 4, the haptic part 40 has anexpansion zone 41 comprising an annular bellows 42 having two annularundulations 43 and 44. The first undulation 43 is situated in theimmediate vicinity of the periphery 31 of the optical part 30 and isopen on the anterior side. The second undulation 44 extendscircumferentially around the first undulation and is open on theposterior side. In the preferred form shown here, the bellows 42 issubstantially sinusoidal in radial section. However, the secondundulation is deeper and wider than the first undulation.

The depth of the first undulation is preferably from 0.40 mm to 0.70 mmand that of the second undulation is preferably from 0.6 mm to 1.0 mm.The first undulation 43 subtends an angle from 50° to 70° and the secondundulation 44 subtends an angle from 500 to 700. The thickness of thehaptic part 40 in the bellows shaped expansion zone is of the order of0.15 mm and that of the haptic part in the peripheral zone is 0.3 mm.The haptic part 40 comprises an annular peripheral gutter 46. Thethickness of the haptic part 40 in the zone comprising the peripheralgutter is substantially greater than that in the zone comprising thebellows 42 and this zone is therefore substantially more rigid than theradial expansion zone 41. The gutter 46 has a concave anterior surface48 and a convex posterior surface 49 that are substantially concentric.The gutter subtends an angle at the center from 90° to 180°, and moreparticularly of the order of 150°. The peripheral gutter has a maximumwidth in the axial direction from 0.5 mm to 1.5 mm. The planeperpendicular to the optical axis A-A of the optical part 30 in thelargest diameter of zone the gutter passes through the periphery 31 ofthe optical part 30 or is slightly offset forward of this periphery.Once implanted, the largest diameter zone of the gutter is aligned withthe equator of the capsular sac SC.

In the third embodiment, shown in FIGS. 3 and 4, the haptic part 40extends all around the optical part 30 and is annularly continuous.

As shown diagrammatically in FIG. 8, the length L3 of the haptic part 40between the periphery 31 of the optical part and the peripheral edgeportion 46 of the radial expansion zone 41 in the rest state is of theorder of 2.4 mm to 2.8 mm and always substantially less than the lengthL4 of the haptic part 40 between the periphery 31 of the optical partand the peripheral edge portion 46 of the radial expansion zone 41 inthe elongated state, which is of the order of 3 mm to 4 mm, afterreduction or elimination of the undulations.

In a variant shown in FIG. 17 of this third embodiment, the posteriorsurface 47 b of the gutter is provided with a plurality of bosses orprotrusions 49 b that are preferably of rounded shape. They cooperatewith the capsular sac at the equator and are adapted to prevent theformation of or to reduce the size of transverse or radial creasesbetween the periphery of the optical part 30 and the gutter of thehaptic part 40 upon contraction of the periphery of the haptic part fornear vision.

FIGS. 12 and 13 show the implant from FIGS. 3 and 4 implanted in acapsular sac SC, respectively in a rest position for far vision and in amaximum accommodation position. The choice of materials is the same asfor the embodiment of FIGS. 1 and 2 and the implantation method is alsothe same.

In the rest position for far vision of the third embodiment, shown inFIG. 12, the convex posterior surface 47 of the gutter 46 is in contactwith the capsular sac facing the equatorial zone of the zonules Z. Thecomplementarity of this convex posterior surface and the correspondingpart of the capsular sac constitutes a barrier to migration ofepithelial cells towards the center of the posterior capsule CP andensures good separation between the anterior and posterior leaves of thecapsular sac, thereby restoring the fan-shaped termination of the zonuleat the equator of the crystalline sac of aphakic eye.

This third embodiment of an accommodative intraocular lens functions insubstantially the same manner as the first embodiment. Upon forwardmovement of the optical part for accommodation, the depth of theundulations decreases, or they even disappear, the haptic partprogressively adopting a substantially frustoconical shape between theperiphery of the optical part and the gutter.

FIGS. 5 and 6 show a fourth embodiment of an accommodative intraocularlens 3 which comprises an optical part 50 and a haptic part 60. Theoptical part 50 shown has a biconvex shape. Other shapes may be adopted.

In the embodiment of FIGS. 5 and 6, the haptic part 60 has an annularand substantially plane zone extending between the periphery 51 of theoptical part 50 and a peripheral edge portion 66 with square corners 67,68. In this embodiment, the radial expansion zone 61 is annular andconsists at least in part of the annular zone between the periphery 51of the optical part and the peripheral edge portion 66, and is made froma less rigid material and therefore has a higher elasticity. It isadapted to elongate on passing from the rest position to theaccommodation position, and its inherent elasticity ensures that theoptical part returns to the rest position when the vitreoushyperpressure and the position of the apex of the ciliary muscle revertto their initial values. In the rest position, the optical part ispreferably slightly forward of, or where applicable in, a planeperpendicular to the optical axis and passing through the middle of thearea of contact of the peripheral edge portion of the haptic part withthe capsular sac.

In variants that are not shown of this fourth embodiment, the hapticpart 60 may comprise two haptic members of the type shown in FIG. 18 orin FIGS. 21 and 22, disposed like those shown in FIG. 18.

In another variant that is not shown of this fourth embodiment, theplane annular zone is replaced partly or entirely by a bellows such asthat shown in FIGS. 1 and 2 or in FIGS. 3 and 4. All or part of abellows of this kind is therefore made from a material that is lessrigid and therefore more elastic than the material of the peripheraledge portion, with the result that expansion is obtained in part throughthe reduction in the depth of, or the elimination of, the undulationsand in part by the elongation of the zone formed of the material havinga higher elasticity.

A two-material implant conforming to this fourth embodiment ispreferably obtained by modifying the chemical and structuralcharacteristics of the starting material, as described in publishedFrench patent application number 2.779.940, for example. It goes withoutsaying that any other material or combination of materials may be used,on condition that the geometry and the functions of the implant of thepresent invention are retained. As shown diagrammatically in FIG. 9, inthis embodiment the length L5 of the haptic part 60 between theperiphery 51 of the optical part and the peripheral edge portion 66 ofthe radial expansion zone 61 in the rest state is of the order of 2.4 mmto 2.8 mm and always significantly less than the length L6 of the hapticpart 60 between the periphery 51 of the optical part and the peripheraledge portion 66 of the radial expansion zone 61 in the elongated state,which is of the order of 3 mm to 4 mm.

FIGS. 14 and 15 show the implant of FIGS. 5 and 6 and its variantsimplanted in a capsular sac, respectively in the rest position for farvision and in the maximum accommodation position. The implantationmethod is the same as already described in relation to the firstembodiment.

In the rest position for far vision represented in FIG. 15, the edge 66is in contact through anterior and posterior square corners 67, 68 ofthe type already described with reference to the first embodiment andhaving the same functions.

This third embodiment of an accommodative intraocular lens functions insubstantially the same way as described with reference to the otherembodiments. Upon forward movement of the optical part foraccommodation, the radial expansion zone is stretched, with the resultthat the distance between the periphery 51 of the optical part 50 andthe peripheral edge portion 66 of the haptic part 60 is increased. Ifthe radial expansion zone comprises one or more undulations, as in thevariants of this embodiment, the latter are progressively reduced indepth and may even disappear when the optical part reaches its maximumaccommodation position. In that position, the annular part 66 assumes asubstantially frustoconical shape between the periphery of the opticalpart and the peripheral edge portion. The combination of the bellows anda material having a higher elasticity allows greater axial displacementfor the purposes of accommodation.

Of course, the present invention is not limited to the embodimentsdescribed and shown, and encompasses any variant execution thereof. Forexample, the undulations in the haptic part are preferably sinusoidal,but other shapes may be suitable. Similarly, the thickness of the radialexpansion zone may be uniform or vary. Likewise, when gaps and notchesare provided about the axis of the optical part, their number and shapemay vary. Finally, the optical part may comprise zones of rigid materialand other zones of flexible material, allowing the optical part to befolded or rolled in order to insert it through a small incision.Configurations may be adopted for the peripheral zone of the haptic partother than a peripheral edge portion with a square corner or sharp edgeand a peripheral edge portion consisting of a gutter.

1. Accommodative intraocular lens for implantation in the capsular sac,comprising a central optical part and a peripheral haptic part, theoptical part having a forward accommodation position and a rest positionfor far vision, characterized in that the haptic part (20, 40, 60)comprises a radial expansion zone (21, 21A, 21B, 21C, 21D, 21F, 41, 61)allowing displacement of the optical part (10, 30, 50) towards theforward position.
 2. Intraocular lens, characterized in that the radialexpansion zone (21, 21A, 21B, 21C, 21D, 21F, 41) comprises a bellows(22, 22A, 22B, 22C, 22D, 22F, 42).
 3. Intraocular lens according toclaim 1, characterized in that the radial expansion zone (21, 21A, 21B,21C, 21D, 21F, 41) comprises at least one undulation (23, 24, 25, 43,44).
 4. Intraocular lens according to claim 1, characterized in that theradial expansion zone (21, 21B, 41, 61) is substantially annular andextends circumferentially around the optical part.
 5. Intraocular lensaccording to claim 1, characterized in that the haptic part (20C, 20F)comprises two symmetrical and diametrically opposite haptic members(21C, 21F).
 6. Intraocular lens according to claim 5, characterized inthat each haptic member has a circumference at the periphery of thehaptic part greater than the circumference at the junction with theoptical part (10).
 7. Intraocular lens according to claim 5,characterized in that the haptic part comprises at least threecircumferentially spaced haptic members.
 8. Intraocular lens accordingto claim 5, characterized in that the gaps between the haptic membershave the same circumference.
 9. Intraocular lens according to claim 3characterized in that the depth of the undulation(s) (23, 24, 25, 43,44) is significantly reduced or eliminated in the forward position. 10.Intraocular lens according to claim 1, characterized in that itcomprises a plurality of symmetrical radial notches (27A) open at theperiphery of the haptic part (20) and in that the notches (27A) passpartly or totally through the annular undulation(s).
 11. Intraocularlens according to claim 3, characterized in that there are at least twoundulations of which one is open on the anterior side (23, 43) and theother or another is open on the posterior side (24, 44).
 12. Intraocularlens according to claim 11, characterized in that the undulation (23,43) open on the anterior side is formed at the periphery (11, 31) of theoptical part (10, 30) and the undulation (24, 44) that is open on theposterior side extends around the undulation (23, 43) that is open onthe anterior side.
 13. Intraocular lens according to claim 12,characterized in that the undulation that is open on the anterior sideis formed at the periphery of the optical part and the undulation thatis open on the anterior side extends around the undulation that is openon the posterior side.
 14. Intraocular lens according to claim 12,characterized in that the two undulations (23, 24, 43, 44) aresubstantially sinusoidal in radial section.
 15. Intraocular lensaccording to claim 12, characterized in that, in the rest state of thelens, the bottom of the undulation (23) that is open on the anteriorside is situated rearwardly of the periphery of the optical part (10).16. Intraocular lens according to claim 12, characterized in that thebottom of the undulation that is open on the posterior side (44) issituated forwardly of the periphery of the optical part.
 17. Intraocularlens according to claim 1, characterized in that the radial expansionzone (21, 41, 61) extends from the periphery of the optical part (10,30, 50).
 18. Intraocular lens according to claim 9, characterized inthat each undulation (23, 24, 25, 43, 44) subtends an angle from 50° to70°.
 19. Intraocular lens according to claim 1, characterized in thatthe haptic part (20, 40, 60) comprises a peripheral edge portion (26,26C, 26D, 26F, 66) with anterior square corners (27, 27C, 27F, 67) andposterior square corners (28, 28C, 28F, 68).
 20. Intraocular lensaccording to claim 1, characterized in that the haptic part (20, 40, 60)is circumferentially continuous over the whole of its radial dimension.21. Intraocular lens according to claim 1, characterized in that theradial expansion zone (61) is more flexible than the remainder of thehaptic part (60).
 22. Intraocular lens according to claim 21,characterized in that the radial expansion zone (61) comprises noundulations.
 23. Intraocular lens according to claim 18, characterizedin that the haptic part (40) comprises a peripheral gutter (46, 46B)whose maximum width in the axial direction is from 0.5 mm to 1.5 mm. 24.Intraocular lens according to claim 23, characterized in that theexterior surface of the peripheral gutter (46B) in its greatest diameterzone comprises protrusions or bosses (49B).
 25. Intraocular lensaccording to claim 23, characterized in that the peripheral gutter (46)has a rounded external surface subtending an angle at the center from90° to 180°.
 26. Intraocular lens according to claim 1, characterized inthat the haptic part (20) comprises a plurality of radial arms (20D)extending between the peripheral edge portion of the optical part (11D)and the peripheral edge portion of the haptic part (26D) and formingclosed contour gaps (29D) between them.